package dao.impl;

import dao.UserDao;
import pojo.User;

import java.sql.*;
import java.util.ArrayList;
import java.util.List;

public class UserDaoimpl implements UserDao {
    List<User> users = new ArrayList<>();//集合,保存数据
    Connection connection=null;
    ResultSet resultSet = null;
    PreparedStatement preparedStatement =null;
    @Override
    public List<User> findAll() {
        //jdbc 操作
        //jdbc操作数据库 查询
        //1.加载驱动
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            //2.获取连接(url username password)
            String url = "jdbc:mysql://127.0.0.1:3306/jdbc?characterEncoding=utf-8";
             connection = DriverManager.getConnection(url, "root", "526874");
//            if (connection!=null){
//                System.out.println("连接成功");
//            }
            //3.写sql
            String sql = "select * from t1";
            //4.预编译sql
             preparedStatement = connection.prepareStatement(sql);
            //5.有参数设置参数
            //6.执行sql
             resultSet = preparedStatement.executeQuery();
            //7.遍历结果集
            while (resultSet.next()) {
                User user = new User();
                user.setId(resultSet.getInt(1));
                user.setName(resultSet.getString(2));
                user.setPass(resultSet.getString(3));
                //把对象添加到集合中
                users.add(user);
            }
            return users;
        }catch (ClassNotFoundException e) {
            throw new RuntimeException(e);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        } finally {
            try{
                if (resultSet!=null) {
                    resultSet.close();
                }
                if (preparedStatement!=null){
                    preparedStatement.close();
                }
                if (connection!=null){
                    connection.close();
                }
            }catch (SQLException e){
                throw new RuntimeException(e);
            }
        }
    }
}
